bethke



J. P. BETHKE.

UFTING MAGNET.

APPLICATION FILED DEC.4. 19H. 1,316,672. PatentedSept. 23, 1919.

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i. P. BETHKE.

LIFUNG MAGNET.

APPLICATION FILED 050.4.19n.

Patented Sept. 23, 1919.

2 SHEETS-SHEET 2.

avlmntoz UNITED STATES PATENT OFFICE..-

J'OHIT P. BE'IHKE, OI MILWAUKEE, WISCONSIN, ASSIbNOR TO DINGS MAGNETICSEPABATOE 00., O1 MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

LIF'I'ING-MAGNET Specification of Letters Patent.

Patented Sept. 23, 1919.

To all whom it may concern:

Be it known that I, JOHN P. Bn'rnnn, a citizen of the United States, andresldent of Milwaukee, in the county of Milwaukee and State ofWisconsin, have invented new and useful Improvements in Lifting-Magnets,of which the following is a description, reference being bad to theaccompanying drawings, which are a part of this specification.

The invention relates to lifting magnets and has for its objects toprovide a magnet which will have a large lifting capacityin proportionto its own weight, one in which the coils for energizing the magnet canbe economically made and readily assembled within the body of the magnetand one in which the magnet shall have its magnetic force uniformlydistributed over its entire surface.

A further object of the invention is to provide meansfor arran 'ng thecoils in series in such a manner 't at direct current of varyingvoltage, such as, either 110 or 220 volts, may beutilized in energizingthe same, without any change in the winding of the coils.

A further object of the invention is to provide heat radiating surfacesof extensive proportions as compared to the coils so that the heatgenerated within the coil may be readily dissi ated to the outsidethereof and thus allow t lie winding to be worked at a ver hi h currentdensity.

not or object of the invention is to provide a magnet in which the bodyis in one piecefland' in which the non-magnetic lates covering the coilsare held in place y the cores of the coils besides being socured to thebody at their outer edges.

Lifting magnets, of the type to which my invention relates, are used forthe purpose of lifting heavy loads, such as lar sheets of steel, largecastings, billets or 0t er magnetic material, and are usually suspendedfrom a crane or other lifting-device. In the magnets of the prior art inwhich the energizing winding consisted of a single coil, it has beenfound that the magnetic lines of force converging toward the center,concentrate there, with the result that the magnet will lift less aroundits outer edge than in the center due to this convergence of lines offorceiand consequently this is pe of magnet is not as efiicient as onein which the lines of force are evenly distributed over the entire,lifting face of the magnet. In the present invention the arrangement ofthe coils in spaced relation to each other and the passage of themagnetic lines of force from the center of these coils to theinner and.Quter portions of the body of the magnet enable me to obtain higheiliciency because of uniform distribution of the magnetic lines offorce.

The invention further consists in the several features hereinafter setforth.

In the drawings:

Figure 1 is a top view of the magnet embodving the invention;

Fig. 2 is a section taken on the line 2-2 of Fig. 1;

Fig. 3 is a section taken onthe line 33 of Fig. 15

Fig. 4 1s a section taken on the line 4-4 of Fig. 2;

Fig. 5 is a diagrammatic'view of the electrical circuits for the coils.

In the drawings, the numeral 5 desi at'es the body or frame of themagnet consisting of a single circular casting of magnetic materialprovided with a central opening-6, for ventilating purposes, and aplurality of coil pockets or chambers 7 which are preferably radiallydisposed and symmetrical] arranged and spaced from each other. 11 thedrawings I show the coil chambers arranged substantially equidistantfrom the center of' the body of the magnet.

lncased within each of the chambhrsl a spool 9 of magnetic material.'Each 9 is removaby mounted upon a cylindrical core 10 of magneticmaterial. The centers of the spools 9 together with the'cores 10constitute the inner poles of the magnets when they; are in place withinthe body.

The upper ends of the cores I0 fit into the cy:

is .an energizing coil 8 which is wound upon tral threaded aperture 15of a circular nonmagnetic plate 16 which secures its coil in place andcovers up the bottom of the coil.

The non magnetic plates 16 are also threadedton their outer edges 17 toconnect with threaded portions 18 of the magnet body so that said platemay be screwed and drawn up tightly into said body thereby providing atight joint to prevent the passage of moisture into the coils. While asshown the coils are surrounded on all sides by the avalls of the body,these Walls are of such thickness that the heat which is generatedwithin them will be readily dissiated and the opening in the center ofthe mdy together with the depressions 19 in the to) also assist thedissipation of heat.

Each energizing coil. is thoroughly insu lated in any well known mannerand when the coils are placed in position within the chambers they arescaled up against exposurc to moisture by introducin awaten proofinsulating compound to ll up the empty space as is well understood bythose skilled in the art.

Vertical channels 20 and horizontal chair nels 21 are formed in the bodyin the walls of the chambers 7 to receive the conductors leading to andfrom the energizing coils, said channels communicating with short ducts22 which lead into an annular recess 7 23 in the top of the body whichis covered over by an angular annular ring 24 suitably secured to thebody, said ring and recess formin an annular protected pocket in whichthe ead wires for the magnets are disposed and protected from injury.

Referring to Fig. 5 it will be noted that the coils 8 are connected inseries and the terminals 25 are secured to binding posts 26 carried bythe ring 24, said posts also serving to secure the ends of the mainconductors to said magnet, these terminals being protected by a cap 27.

To provide for use of the magnet on varying current voltage withoutchanging the coils I provide a conductor 2'8 which is se cured to abinding post 29 and is connected to the conductor for the coils so as todivide the coil circuit and put the coils in parallel with each other.Thus when the main conductors. are secured tothe posts 25 the coils arein series and the magnet runs at high voltage. When it'is desired tooperate the magnet on a lower voltage, one of the main conductors isconnected to the post 39 thus placing the coils in parallel and reducingthe v0 age. This permits the magnet to be operated either on a 220 or110 volt circuit.

The to of the magnet is provided with integral ugs 30 to provide forsuspending the magnet from a suitable chain or other suspension meansfor raising, lowering and transporting the magnet.

A further feature of the invention is the provision of an annularconcave recess 30 adjacent the opening 6 and at the bottomof the body.This recess is designed to receive and seat within it the upper end ofwhat is called a skull cracker ball which is a-heavy steel or iron hallused to crack up castings, old iron and billets by letting the ball fallfrom a considerable height, the use of the hall being clearly understoodby those skilled in this art. The recess rovides for an accuratecentering of the scull cracker ball within the center .of the magnet andthus any tendenry of over-balancing the magnot which occurs .in formerconstructions is prevented.

W'ith this construction when the coils 8 are energized the magneticlines of force flow from the centers of the coils or inner poles towardthat portion of the body of the magnet surrounding them, the main fluxpassing from the inner poles toward the outer and inner portions of thebody so that the lines of force are uniformly distributed on the surfaceof the magnet.

What 1 claim as my invention is:

1. In a lifting magnet, the combination of a body of magnetic materialprovided with a plurality of coil chambers opening into the lifting faceof the n'iagnet, energizing coils incased in said chambers, ren'iovablecores for said coils, means for detachably securing the inner ends ofsaid cores to the body of the magnet. removable non-magnetic platescovering the bottom of the coils and heads on said cores engaging aportion of the outer faces of said plates.

2. In a lifting magnet. the combination of a body of magnetic materialprovided with a plurality of coil chambers opening into the lifting faceof the magnet, energizing coils encased in said chambers, cores for-said coils removably secured at their inner ends to the body of themagnet and having a threaded outer end portion and removablenon-magnetic plates-covering the bottom of the coils and having threadedbores engaging the threaded portions of said cores.

3. In a lifting magnet, the combination of a bod of n'iagnetic materialprovided with a p urality of coil. chambers opening into the liftingface of the magnet, energizing coils disposed in said chan'ibers, coresfor said coils removably secured at their inner ends to the body of-themagnet and having a threaded outer end portion, and

removable non-magnetic lates covering the bottom of the coils and iavingthreaded bores engaging the threaded portions of said cores and threadederiplter'ies engaging threaded portions of tile body adjacent saidchambers.

4. In a lifting magnet, the combination -w th a body portion of magneticmaterial having a central opening therein, of a recess in the bodyadjacent said opening and extending around the same, and a cover membersecured to said body adjacent said recess, said recess and cover memberforming an inclosed channel for receiving conductor wires.

5. In a lifting magnet, the combination with a body of magnetic materialhaving a central opening therein, of an annular recess in the too ofsaid body adjacent said opening, an annular ring of angle iron securedto said body adjacent said recess, said recess and rin forming aninclosed channel to receive amf protect the conductor wires. 6. In aliftin magnet, the combination .of an annular Eody of magnetic materialprovided with a lurality of radially disposed symmetrica y arrangedpockets opening into the lifting face of the magnet, energizing coilsincased in said pockets, said body being provided with a centrallydisposed ventilating assageway and said pockets being space from eachother and from the outer and inner sides of the body to form radiatingsurfaces to dissi ate heat andpermit theicoils to be wor ed at a highcurrent density, and cores for the 60118 centrall disposed therein andforming magnetic 0 es having pole faces disposed substantia ly in theplane of the lifting face of the magnet.

7, Ina lifting in st, the combination of a one piece annulai' fid ofmagnetic material provided with a p urality of radially disposedsymmetrically an'a ed pockets opening into the lifting face 0 the ma et,

-energizlng coils incased in said poc ets, cores i 01; said coilssecured to said body and magnetic poles having pole faces of greaterdiameter than the body of the cores and disposed outwardly of the coilsand substantially in the plane of the lifting face of the magnet, andnon-magnetic plates covering the bottoms of the coils and held in placeby a shoulder on said cores defined by the pole faces being of greaterdiameter than their body portion and by a connection with the body.

8. In a lifting magnet, the combination of a one piece annular bod ofmagnetic material provided with a p urality of radially disposedsymmetrically arran ed cylindrical pockets opening into the lifting faceof the magnet, said pockets being spaced from each other and from theouter and inner sides of the body to form relatively thin walls and theouter sides of the Walls conforming to the curved outer portions of thepockets to within a comparatively short distance from the bottom of thebody to form a lurality of re cesses in the top portion 0? the bodyadjacent its outer edge wherebytthe body is provided with heat radiatingsurfaces of extensive proportions as compared with the coils so that theheat generated within the coils ma be readily dissipated and thus permitthe coils to be worked at a high current density, and energizing coilsincased within said pockets and electrically connected together. i

In testimony whereof,I aflix my signature.

JOHN P. BETHKE.

